Plastic containers such as bottles of water are manufactured and filled according to different methods including blow moulding or stretch-blow moulding.
According to one of these known methods a plastic preform is first manufactured through an injection molding process and then heated before being positioned inside a mould.
The preform usually takes the form of a cylindrical tube of sod at its bottom end and open at its opposite end.
Once the preform has been positioned within the mould only the open end of the preform is visible from above the mould.
This method makes use of a stretch rod which is downwardly engaged into the open end of the preform so as to abut against the closed bottom end thereof. The stretch rod is further actuated to be urged against the closed end, thereby resulting in stretching the preform.
After the stretching phase has been initiated a liquid is also injected into the preform through its open end. This liquid injection causes expansion of the preform until coming into contact with the inner was of the mould, thereby achieving the final shape of the bottle.
The bottle which has been thus manufactured and filled within the mould has then to be sealed with a cap.
In this respect, the mould is opened and the bottle filled with liquid is transferred to a station provided with a capping head.
A cap is placed within the capping head and the latter is rotated around the threaded neck of the bottle so as to screw the cap around the neck.
Although this method proves to be satisfactory, there is nevertheless a need to make the blowing, filling and capping process easier.